International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net DYNAMIC ANALYSIS OF TALL TUBULAR STEEL STRUCTURES FOR DIFFERENT GEOMETRIC CONFIGURATIONS Hemappa S Yaligar, Ramya B V2, Sowmya R H3 1 Post Graduate in Structural Engineering, BIET College, Davanagere-577004, India Asst, Professor, M. Tech Structural Engineering, BIET College, Davanagere, India 3 Asst, Professor, M.Tech Structural Engineering, BIET College, Davanagere , India ------------------------------------------------------------------------***------------------------------------------------------------------2 Abstract - In structural engineering, the structural frames are the load resisting systems. The analysis and design of structures particularly tall structures needs appropriate analysis methods, precise design concepts along with preliminary designs aided with optimisation, in order to resist the gravity as well as lateral load, so that structure remains safe thought its life span. In extremely tall buildings stiffness plays a very important role in controlling the global displacements. Hence new structural systems are developed by combining the previous structural systems in order to resist effectively the lateral loads due to earthquake and wind and to limit global displacements, drifts and accelerations under control. The tube structural concept had become more popular structural systems particularly for high rise steel structures. To understand the behaviour of the tall tubular steel structures for different geometric configurations like square, rectangle, triangular, hexagonal shapes in plan, in comparison with the steel beam column rigid frame system, were analysed using ETABS 2016. The effect of geometric configurations on behaviour of tall tubular steel structures are summarised using the obtained results, by concluding the optimum geometric configuration for tall tubular steel structures. Key Words: Tube structure, Earthquake zones, wind load, Base shear, Story drift, Story displacement and ETABS. 1. INTRODUCTION The appropriate analysis methods are used for structural design and analysis of structures especially for multi-story structures, accurate design ideas alongside with initial designs supported with optimization, in order to withstand the vertical as well as horizontal load, so that building stay safe thought its life period. The major vital standard in structural engineering is strength, stability and serviceability of the structures. The purpose of structural engineers for high rise buildings is to resist the lateral forces like earth quake and wind force that are acting on structure. The purpose of structural engineers for high rise buildings is to resist the lateral forces like earth quake and wind force that are acting on structure. Many structural engineers carried out lot of work to analyses the effect of lateral forces regarding its height and they formulated some criteria to keep minimum deflection or fixed deflection for the forces © 2019, IRJET | Impact Factor value: 7.211 | acting on the structure. Among which the geometry of structure is also one of the important factor so in this study we have considered various geometry of structures. 1.1 Characteristics and importance of structural systems In extremely developed urban areas there is a deficiency of land hence very large requirement for tall structural systems, increase in requirement for residential space and business, technical innovations, alteration in structural systems concept of town sea line and social dream to construct higher. The stiffness plays a very important role in tall buildings to controlling the overall displacements. Sao original structural systems are constructed by combining the earlier systems in order to co1unater attack adequately the lateral forces from earthquake and wind and accelerations, drifts and to minimize overall displacements or top put it in control. The structural system transmission loads from corresponding structural members. The members which carry’s loads are considered to be structural system and they need to be designed all other members are nonstructural members. In this metropolitan world the necessity of super tall structures are very necessary. The structures may go up to 300 to 500m height as a structural engineer we should ensure its safety as whole structure and as a unit for that purpose different structural system were developed. 1.2 STRUCTURAL SYSTEM CLASSIFICATIONS Structural systems are classified into 4 types Type 1 – Shear Frames Type 2 – Interacting frames Type 3 – Partial Tubular frames Type 4 – Tubular Systems 1.3 Classification of Tube structures Basic forms of tubular systems are Framed tube Braced tube ISO 9001:2008 Certified Journal | Page 1768 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 Bundled tube Tube-in-tube Tubed mega frame www.irjet.net 9 Grade of concrete M30 (Deck Slab) 10 Column Sections Built up (ISWB 600) 1.4 Objectives studies 11 Beam Sections ISMB 600 1. 12 Deck Section 200 mm thick 13 Live load 4 KN/m2 14 Floor finish 1.5 KN/m2 15 External Glazing 2.0 KN/m 16 Location of Building In Moderate intensity 17 Soil type (Z-II) type II (Medium) 18 Importance factor 1.0 19 Response reduction factor 5.0 2. 3. 4. To know the behavior of different geometric Configurations of tall tubular steel structures like square, rectangle, triangular, hexagonal shapes in plan, comparison with the square steel moment resisting frames system. Equivalent static method is used to carry out earth quake Analysis, referring IS1893-2002 and ETABS 2016 is used to carry out the dynamic time history analysis. Also wind analysis is carried out to understand the behavior under the wind loads. Base shear, story displacement and peak displacement, story drift and acceleration are found out for all geometric configurations. By using obtained results the effect of geometric configurations on behavior of tall tubular steel structures are summarized. 20 Fundamental Natural Period 6.382 seconds 2. DATA FOR DEVELOPING THE MODEL Using ETAB 2016 Structural modeling of steel framed tall tubular structure is made for hexagon shape geometric configuration, with a regular steel moment resisting frame section. All the models having equal number of stories which is 88 numbers and constant floor area constant diaphragm to take lateral loads and transmits to beams are provided for all the models to obtain the consistent results for lighting, ventilation and service criteria a central core is permitted. Table-1: Parameters Considered For the Development of Structure SL NO PARAMETERS REMARKS 1 Type of Structure Steel Moment Resisting Framed tube 2.1 Dynamic Time History Analysis Linear or nonlinear valuation of dynamic structural response provided by time-history analysis for loading which may differ according to the fixed time function. By using either modal or direct integration methods dynamic equilibrium equations, are solved. From the end of the past analysis Initial conditions may be place by continuing the structural state. The ELCENTRO time history data is considered in the present study, the following specifications of elcentro is given below. Table-2: ELCENTRO Time history Data Specifications SL NO 1 SPECIFICATIONS REMARKS Location “Imperial Valley” 2 Plan Configurations Square, Rectangular, Triangular and Hexagonal 2 Date of occurred 3 4 Story details Each floor height G+87 (88 Storied) 3.6m 5 6 Total building Totalheight Floor area 316.8m 3550m2 3 4 5 6 Time duration Station Direction Horizontal Units of acceleration (g) 7 Type of Building Office Building 8 Grade Steel 345Garde © 2019, IRJET | Impact Factor value: 7.211 7 8 | earthquake 19th May 1940 Number of time instants Sampling time(Δt) 4:39am “Ell Centro A rray#9” 1800 9.81m/s2(acceleratio n of gravity) 4000 0.01 s (f= 100 Hz) ISO 9001:2008 Certified Journal | Page 1769 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net c) Model 3: structures Plan of rectangle Framed tube Fig-1: Time History Data for El-Centro 2.2 W1IND ANALYSIS Wind loads is considered as per IS 875:1987 Wind speed Vb = 33 m/s Terrain Category = 4 Structure Class = c Risk Co-efficient = 1 2.3 DIFFERENT GEOMETRIC CONFIGURATIONS FRAMED TUBE STRUCTURES Fig3. Plan of rectangle Framed tube structures d) Model 4: Plan of triangle Framed tube structures OF a) Model 1: Plan of square steel moment resisting framed tube structures Fig4. Plan of triangle Framed tube structures e) Model 5: Plan of Hexagonal Framed tube structures Fig2. Plan of square steel moment resisting framed tube structures b) Model 2: Plan of square framed tube structures Fig5. Plan of Hexagonal Framed tube structures Fig3. Plan of square framed tube structures © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1770 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net 3. ANALYSIS OF RESULTS AND DISCUSSIONS 3.2 RESULTS FOR EARTH QUAKE ANALYSIS a) MAXIMUM BASE SHEAR 3.1 MODAL ANALYSIS For all geometric configurations modal analysis has been carried out and listed the frequencies and time period in Table 4 and Table 5 respectively. For hexagonal tube structure having maximum compared to all other structure, time period for hexagonal tube structure is 34% high than that of square steel moment resisting frame structure and 29% compared to all other tube structures. For square tube structure having Maximum frequency is found i.e 0.063 cycles/sec. a) Mode vs. Time Period Chart 3. Maximum base shear 3.3 STORY DISPLACEMENTS FOR EARTHQUAKE LOADS a)Story vs Displacement Chart 1. Mode V/s Time period for different tube structures b) Mode vs. Frequency Chart 4:Story Displacements graph for earthquake load b) Story vs Drift ratio Chart 2: Mode V/s frequency for different models Chart 5: Story Drifts graph for earthquake load © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1771 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net 3.4 DYNAMIC TIME HISTORY ANALYSIS RESULTS A) SQUARE STEEL MOMENT RESISTING FRAME C) RECTANGULAR FRAMED TUBE STRUCTURES IN PLAN B) SQUARE FRAMED TUBE STRUCTURES IN PLAN D) TRIANGULAR FRAMED TUBE STRUCTURES IN PLAN © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1772 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net 3.5 RESULTS FOR WIND ANALYSIS STORY DISPLACEMENTS FOR WIND LOADS a) Story vs Displacement Chart 6. Story Displacements graph for – Wind Analysis a) Story vs Drift ratio E) HEXAGONAL FRAMED TUBE STRUCTURE IN PLAN Chart 7. Story Drift ratio graph for – Wind Analysis 4 © 2019, IRJET | Impact Factor value: 7.211 | CONCLUSIONS From the above results and discussions of all modal analysis, it can be terminated that hexagonal tube structure is having higher time period i.e., 25.42 seconds and having lesser frequency 0.040 cycles per second. Hence from point of view of time period and frequency this framed tube structures can be considered as stable. From the lateral load analysis both earthquake and wind analysis, we found maximum displacement and story drifts are encountered for hexagonal shape framed tube structures. The behaviour and responses of Square and triangular frame tube structural systems are ISO 9001:2008 Certified Journal | Page 1773 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 p-ISSN: 2395-0072 www.irjet.net similar in case of earthquake and wind load analysis. To compare equivalent static analysis the dynamic time history analysis results are lower. Hence to understand the correct behaviour of the high rise structural system, dynamic analysis is preferable. Form the above results and discussions it can be decided that tube structure is preferable for high rise structures in place of conventional beam column moment resisting frame steel system. [8]Richard, A. Ellis and David P. Billington (2003) “Construction history of the composite framed tube structural system.” Proceedings of the First International Congress on Construction History, Madrid, 20th-24th January 2003, ed. S. Huerta, Madrid: I. Juan de Herrera, SEdHC, ETSAM, A. E. Benvenuto, COAM, F. Dragados, 2003. BIOGRAPHIES 4.1 SCOPE OF FUTURE WORK dynamic analysis of tall tube-in-tube structures by finite story method.” Engineering Structures, Vol. 18, (7), 515527. In hexagonal frame tube structure the displacement, story drifts are reduced by using additional structural systems like diagrids, steel plate and shear walls. For all geometric configurations mega braces can be used to reduce the displacement. In complex shape tubular structures are also analysed. For same geometric configurations tube in tube structures can be analysed. REFERENCES [1] Arvind, J.S. and Helen Santhi, M. (2015) “Effect of Column Shortening on the Behaviour of Tubular Structures.” Indian Journal of Science and Technology, Vol 8(36). [2] Dileep, N., and Renjith, R. (2015) “Analytical investigation on the performance of tube- in-tube structures subjected to lateral loads.”International Journal of Technical Research and Applications. Vol. 3, (4), 284288. HEMAPPA S YALIGAR Post Graduate Student Dept. of Civil Engineering BIET College, Davanagere. RAMYA BV Asst. Professor Dept. of Civil Engineering BIET College, Davanagere. SOWMYA R H Asst. Professor Dept. of Civil Engineering BIET College, Davanagere. [3] Han, R.P.S.(1989) “Analysis of framed tube structures of arbitrary sections”. Applied Mathematical Modelling, Vol. 13. [4] Hong, F., Li, Q.S., Tuan, A.Y. and Xu, L. (2009) “Seismic analysis of the world’s tallest building.” Journal of Constructional Steel Research, 65 1206–1215. [5] Nishant, R., and Siddhant, R. (2014) “Structural Forms Systems for Tall Building Structures.”SSRG International Journal of Civil Engineering, (SSRG-IJCE). Vol. 1, (4). [6] Patil, S. and Kalwane U. (2015) “Shear lag in tube structures.” International Journal of Innovative Science, Engineering & Technology. Vol. 2 (3). [7] Pekau, Lin, L. and Zielinski, Z.A. (1996) “Static and © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1774